1. Field of the Invention
This invention relates to treating surface layers of the earth to stabilize the surface layers for foundations, roadways, building and the like.
2. Description of the Prior Art
The prior art is replete with a wide variety of materials that have been employed to stabilize soils, or improve subgrades in surface and subsurface layers for a variety of purposes. The applications have been as varied as improving subgrades for building sites, streets, runways, railroads, dewatering projects and more recently improving the slopes for preventing failure thereof. Of course, pretreating building sites for improving the strength and volume change characteristics of soils has long been a problem plaguing the civil engineer and the architectural engineer. The problems have been varied and the techniques have been varied to try to overcome them. Lime slurries have been worked into the top layers; for example, the top 6-36 inches in depth to improve and stabilize soils or subgrades. This working of lime into the surface layers of the earth has been well publicized. For example, Bulletin 326 entitled "LIME STABILIZATION CONSTRUCTION MANUAL," published by the National Lime Association, Washington, D.C., 1972 chronicles various methods of working lime into the surface layers and the improved results obtained by stabilizing the base. For example, at page 7 there are detailed the improved results of incorporating lime into the soil. That manual even discloses the injection of pebbles of quicklime into the soil. These pebbles of quicklime do not work satisfactorily, however.
Since the advent of the energy crisis, the price of hydrated lime has risen dramatically. Moreover, prices continue to rise steadily as this is a highly energy-dependent system. Furthermore, in certain parts of the United States, difficulty is frequently experienced in obtaining adequate quantities of hydrated lime (calcium hydroxide).
Thus it can be seen that the prior art has not been totally satisfactory in providing an economical process in which the starting materials were always available at an economical price.
Moreover, one of the deficiencies of the prior art has been the attempt to work lime slurry, with or without additives, into the soil during cold weather or the winter season when ambient temperatures would cause the slurry to freeze, either in the mixing tanks, conduits, or pumps; or the cold slurry would not react readily with the soils, since full and final chemical reactions were temperature dependent. Thus there was a limited season and it was desirable that the season be extended by some method.